Grasshopper Plug-In with Python library

Grasshopper Developer
1

Hi,

I’m planning to write a Grasshopper Plug-In that will use a library written in Python.
What would be the best way to go about this?

I assume that the Plug-In itself has to be in C# or some such, right? (I.e., not in, say IronPython.)
In that case, what is the best way to access the Python library.

Thanks,
Thomas

2

RhinoCommon has functions which let you run python scripts. See the Rhino.Runtime.PythonScript class for this in the RhinoCommon SDK

@piac, did we ever release the GhPython with support for creating python based components?

3

Thanks Steve,

So in other words, the approach would be to write a C# plug-in, and call Python via the Python Runtime you mentioned, right?

Thanks,
Thomas

4

Yes, that would be one approach. I mentioned @piac because he wrote another optional approach where everything can be done in python. I’m not sure what the status of that project is though.

5

That temptative approach is in the next Rhino branch. Should that be changed?

6

No, that’s fine. I just couldn’t remember where we were with respect to that functionality.

7

Steve, Giulio,
that sounds like great news for Python scripters. I would personally like to see that in R5 and I suspect a lot of people would too. If R6 is a long way away, a lot of ppl will ask for having that functionality in R5.
Cheers,
Florin

2 Likes
8

Hi Steve,

Thanks for your help so far. It took me a while, but I finally got around to working on this project.
I’m experimenting with running a python script from C# in Grasshopper, which seems to work (ExecuteFile returns True).

However, I’m struggling to understand how to input/output with that script. Here’s my C# code so far:

string path = “C:\python_hello.py”;
Rhino.Runtime.PythonScript rbfopt = Rhino.Runtime.PythonScript.Create();
rbfopt.SetVariable(“hello”, “blank”);
rbfopt.ExecuteFile(path).ToString();
object output = rbfopt.GetVariable(“hello”);
Print(output.ToString());

python_hello.py looks like this:

hello = “Hello Thomas!”

Now, I’d expect “Hello Thomas!” as an output, but I get “blank”.

So, if I run a file, (how) can I access its variables? Alternatively, can I somehow “print” some output?
I guess I can always read and write *.txt files, but I’m hoping that there’s an easier way.

Thanks!
Thomas

9

I found a way to solve my problem:

1 Like
10

Just to be shure I understood this: There will be a way to create “real” components using python (as opposed to using the python-script component)?
Is that already in the R6 WIP? If yes, what is the way to get that WIP?

Cheers
Henning

11

Yep, there’ll be a way to compile Python code. This has been in the works for a while, from what I understand. You might want to check out this discussion.
/SPM

12

Yes. You just need Rhino WIP to test this.